He was known to most people before 1294 as Peter Morrone, sometimes Peter Maiella. He was a hermit, who first lived on Mount Morrone, then on Mount Maiella, in the Ambruzzi area of Italy. He lived in caves and huts and founded a religious order, known as the Celestine Hermits. At the age of 84 on Aug. 29, 1294, Peter would forever be known as Celestine V, the only pope who abdicated — on Dec. 13, 1294 — until Benedict XVI in 2013. On March 5, 1313, Pope Clement V canonized St. Celestine V.

Jon M. Sweeney narrates the story in his well-researched book The Pope Who Quit. Subtitled A True Medieval Tale of Mystery, Death, and Salvation, the book begins with Peter’s birth in a small village in Molise, the most remote region of Italy. By 1230, he had spent three years as a monk at Santa Maria of Faifula, but left the monastery to become a hermit in the mountains.

Nothing is known of his life for the next 50 years! After Pope Nicholas IV died in Rome, 12 cardinals assembled to elect the next pope, but remained in a stalemate for over two years. After reading the signs of his times, Peter, thinking in apocalyptic terms, wrote a letter to Cardinal Latino Malabranca Orsinsi, dean of the Sacred College of Cardinals. The cardinals were in Perugia, still attempting to elect a successor to St. Peter.

After Orsini received Peter’s letter, he nominated Peter to be the next supreme pontiff, and he was elected. After the cardinals sent a delegation to the mountains to find Peter to notify him that he had become the next pope, Celestine V chose to be crowned in L’Aquila. For the length of his short reign he lived in the Kingdom of Naples which was ruled by Charles II. Sweeney does an excellent job of presenting all the politics — both secular and religious — involved before, during, and after Celestine V’s reign.

After Celestine V abdicated, he attempted to return to his hermitage in the mountains, but his successor, Boniface VIII (Cardinal Benedict Gaetani), had Peter found during Christmastime and imprisoned him in Castle Fumone, near Anagni, where he died on May 19, 1296.

“I first heard about Celestine V a decade ago while doing research in Italy for a book about the inheritors of the spiritual legacy of St. Francis,” Sweeney writes. “I wondered how history would be different if Celestine had stayed in power, or if he’d met with any success whatsoever as holy father during the fifteen weeks of his reign.”

The Pope’s Soldiers: A Military History of the Modern Vatican, by David Alvarez (Lawrence, KS: University Press of Kansas, 2011) is a general military history of the papacy from the French Revolution to the present. Alvarez emphasizes military generals and their soldiers, their campaigns, and their battles.

The 429-page book revolves around three generals, primarily reformers of the papal forces: Christophe de Lamoriciere, Hermann Kanzler, and Jules Repond. The four branches of the papal army are well developed: the Palatine Guard, the Noble Guard, the Pontifical Gendarmeria, and the Swiss Guard. By 1970 the Gendarmeria was transformed into the Vigilance Corps, or police force. The only military unit left was the Swiss Guard.

In the introduction to the book, Alvarez makes clear that it is neither a political nor a diplomatic history, although he must place the papal soldiers within the context of events taking place in Rome, Italy and Europe. He considers popes only to the extent that their attitudes and actions impinge upon the preparation and deployment of the papal forces.

After the assassination attempts upon the lives of Pope Paul VI and Pope John Paul II, the Vigilance Corps became more concerned with protecting the pope. They are seen today as plainclothes officers surrounding the pope at any public papal function. In 2002, they were named the Gendarmeria of the Vatican City State; they number 152 men.

Father Boyer, a priest for 37 years, is the author of 33 books primarily in the areas of biblical and liturgical spirituality as well as numerous articles in various magazines, including The Priest, for which he wrote Homily Backgrounds 1987-1993. He teaches in the Religious Studies Department of Missouri State University, Springfield, Mo.